Oil cooler for internal combustion engines



2 Sheets-Sheet 1 al (L H. G. SCHWARZ Filed May 10, 1940 Nov. 4, 1941.

OIL COOLER FOB INTERNAL COMBUSTION ENGINES llllz/JHHH- llllllllll l.d4-J1 lill' 1|| L T l l, x l L E.. 1 w 2 W H. G. scHwARz 2,261,418

Nov. 4, 1941.

OIL COOLER FOR INTERNAL COMBUSTION ENGINES 2 Sheets-Sheet 2 Filed May10, 1940 Patented Nov. 4, 1941 UNITED `STATES OIL COOLER FOR. INTERNALCOMBUSTION ENGINES Henry G. Schwarz, Marshallton, Del.

9 Claims.

This invention relates to an improved oil cooler for internal combustionengines, and more particularly to an improved type of cooler for use inmaintaining the lubricating oil used in aircraft enginesat a desiredtemperature.

As is known, the lubricating oil circulated through the engine orengines of an aircraft tends to become overheated, particularly intemperate or tropical climates, by the great amount of heat liberated bysuch engines, especially when driven at high speeds, and suchoverheating if permitted to continue leads to loss of lubricating effectand eventual carbonization of the oil.

It has accordingly been common practice to provide meansffor cooling theengine oil circulated through aircraft engines. The means heretoforeused comprised essentially honeycomb core radiators in which hot oil tobe cooled was passed through the interior of the'radiator core, and astream of air was passed over the radiator core to dissipate the heat. l

Such coolers are neither efiicientnor satisfactory-in many respects.When located outside the aircraft,in the air stream created by theforward motion of the aircraft, as they must be for great- `estefficiency, they create a heavy drag or resistance, requiring extrapower in the aircraft or reducing the cruising and top speed of thecraft. When located in the engine compartment such coolers must have anadequate air supply, fur- .nished from an inlet duct ending in anair-scoop on the exterior of the aircraft. In such installationsthe'eficiency of the cooler is limited, and the air-scoop creates a veryappreciable drag,

particularly at high speeds.

Even with the cooler located in the wing, and provided with an air inletduct opening on the leading edge of the Wing, so that no scoop is-needed, the presence of the inlet opening causes pacity to prevent theengine oil from overheating even when flying at high tropicaltemperatures.

I furthermore provide in accordance with my invention a cooler providedwith automatic means for maintaining the engine oil temperaturcat anydesired temperature selected by the pilot, which temperature may bechanged at will from time to time.

Essentially the oil cooler in accordance with my invention comprisesmeans for circulating the engine oil in heat interchange relationshipwith a liquefied refrigerant as, for example, sulphur dioxide, methylchloride, ammonia, etc.; means for compressing and condensing therefrigerant, preferably driven from the aircraft engine, means forby-passing a predetermined portion of compressed refrigerant vapor pastthe condenser, and means responsive to the temperature of thecirculating engine oil for automatically controlling the proportion ofrefrigerant vapor by-passed.

The construction and advantages of my improved oil cooler will befurther apparent from a consideration of the accompanying drawings whichillustrate a preferred embodiment of my invention and in which:

Figure 1 is an elevation, partly in section, of a preferred form of aircooler in accordance vwith my invention;

Figure 2 is a section on the line 2-2 in Figure 1, with the compressorand associated piping not shown, for clarity; and

Figure 3 is a detail sectional view of the automatically controlledby-pass valve used in accordance with my invention.

As shown in Figures 1 and 2 the oil cooler comprises a heat interchangeunit A, a compressor B, a by-pass valve assembly C, a condenser D, areceiver E, and a float chamber F, all mounted as a unit. The cooler maybe located anywhere in the aircraft, as in the power plant or nacellesection, or in the wing of a large bomber or transport, but desirably itwill be located as near an engine as possible so that the necessaryconnec,

tions with the engine may be short.

The construction and function of these several units will becomeapparent from the following description of the operation of the cooler.

Hot engine oil from the aircraft engines circulated by the oil pumpthereof is brought to the cooler through a suitable conduit (not shown)and enters the heat interchange unit A of the cooler at I, flows aroundthe bales 3, as shown, over the U-shaped tubes 5 lled with liquefiedrefrigerant supplied from the float-chamber F, to which it gives upheat, and is discharged from the unit at 1, whence it ows back to theengines through a return conduit (not shown). Any desired number oftubes 5 may be positioned within the unit A; in the cooler shown' six ofthem, arranged in three pairs, are used. The inside diameter of thetubes 5 should be suicient to prevent vapor from sealing them againstentry of liquefied refrigerant from the float-chamber F.

Liqueed refrigerant in the tubes 5 will be vaporized by heat taken upfrom the circulating oil and the vapor will collect in the space 9 abovethe liquid level in chamber F, whence it will be withdrawn throughconduit li connected with the suction side of compressor B through acheckvalve I3.

The compressor B, of the positive displacement type, will be driventhrough shaft |5, preferably by means of a flexible drive shaftconnected in any suitable manner to an engine of the aircraft so thatcompressor B will be in operation whenever the aircraft engine isturning over.

The refrigerant vapor, after being compressed by compressor B to apressure at which it may be condensed at ordinary temperatures, passesthrough conduit |1 tothe by-pass valve assembly C, from which aregulated portion of the compressed vapor, determined by the setting ofthe by-pass valve as hereinafter described, passes to the condenser Dthrough conduit I9, while the remainder is by-passed to the low-pressureside of the compressor through conduit 2|.

High-pressure vapor from conduit |9 passes through condensing coil 23 inheat interchange with cold air supplied from outside the aircraft and isthereby liquefied. The liqueed refrigerant ows through conduit 25 fromthe condenser D to the receiver E, from which it is forced, by thepressure in the system, to the oat-chamber F, through conduit 21 andvalve 29, the latter controlled by ioat 3l. A wire mesh strainer 2'8 isprovided at the outlet from receiver E.

The air-inlet 33 for condenser D connected through a conduit (not shown)with the exterior of the aircraft, but no air-scoop is used, and thecondense/r air-outlet 35 is connected by a second conduit (not shown)with the carburetor airscoop (or intake manifold) of the engine. Outsideair is thus sucked through the condenser D as long as the aircraftengine is running..l

As shown in Figure 3 the by-pass valve assembly comprises an inlet port31 connected to conduit I1, an outlet port 39 leading to conduit I9 andcontrolled by valve 4|, and a second outlet port 43 leading to conduit2| and controlled by valve 45. Valves 4| and 45 are both mounted onvalve stem 41 which at one end is guided in a recess in the plug 49 andat the other end extends through the gland 5| into the housing 53.

A thermally responsive bulb 55 of conventional type, filled with areadily expansible solid or liquid is Secured by brackets 56 to the unitA so as to respond to the temperature of the oil flowing therethrough.The bulb 55 is connected by the flexible conduit 51 with a bellows 59mounted in the by-pass assembly C. Upon an increase in temperature ofthe oil flowing through A, the expanslon of the medium lling bulb 55 iscommunicated through conduit 51 to the bellows 59 and the latter expandsagainst the pressure exerted by spring 6|.

The movement of bellows 59 is communicated to the lever 63 and by it tolink 65, whence it is transmitted through an overload release to valvestem 41. The overload release, in housing 53, comprises a yoke 61mounted on the end of valve stem 41 and provided with slots 69, a head1| mounted on the end of link 65 and provided with pins 13 engaged inslots 69 of the yoke 61, and a spring 15 mounted between the yoke 61 andhead 1|. Thus, movement of link 65 is transmitted to valve stem 41through spring 15, which may be designed to yield at, for example, apressure of lbs./sq. inch, and when valve 45 has closed any furtherexpansion of bellows 59 will be taken up in compression of spring 15.

The position of valves 4| and 45 may be altered independently or' anymovement of bellows 59 by means of the oil mounted on the instrumentpanel of the aircraft and calibrated in degrees. Movement of knob 8|temperature regulator 19,`

rotates a gear 83 which in turn rotates pinion 85 connected to the drivewire of exible shaft 81. The opposite end of the shaft 81 is connectedto the screw 89 so that rotation thereof moves the member 9|, in whichlever 63 is pivoted, right or left, and so changes the position ofvalves.4| and 45 and the setting of the automatic control mechanism.

As is apparent, an increase in the temperature of the oil passingthrough unit A will cause bellows 59, actuated by bulb 55, to expand andso move valves 4| and 45 to the left, closing l ort 43 and reducing theamount of refrigerant bypassed through conduit 2|, and increasing thatpassing through .conduit |9 to the condenser. The cooling effect of therefrigerant will thus be increased and the temperature of the oilleaving A lowered.

A decrease in the oil temperature in AI will, in similar manner, permitbellows 59 to be compressed by' spring 6|, and valves 4| and 45 willmove to the right, by-passing more refrigerant and lessening the coolingaccomplished in unit A.

The oil leaving the heat interchange unit A will thus have a.temperature closely approximating that for which the regulator 19 isset, and the pilot by changing regulator 19 may thus control thetemperature to'meet changing conditions.

It will be appreciated that the details of construction and operationhereinbefore set forth are merely illustrative of a specific embodimentof my invention, and that the invention is in no way limited thereby,but is capableof modification in various particulars without departingfrom the scope thereof.

What I claim and desire to protect by Lettersy Patent is:

1. An oil cooler for an internal combustion engine comprising, incombination, a heat interchanger, means for circulating hot engine oilthrough said heat interchanger in `heat interchange relationship with aliquefed refrigerating medium, whereby the refrigeratingmedium is atleast in part vaporized, a compressor for compressing the said vapor toa pressure at which it may be condensed at normal temperatures, and acondenser for condensing the compressed vapor for reuse in the heatinterchanger, said condenser including an air inlet and an air outlet,the latter connected to the carbureter air supply of said engine,whereby air is drawn through said condenser in heat interchangerelationship with said compressed vapor. t

2. An oil cooler for an internal combustion engine comprising, incombination, a heat interchanger, means for circulating hot engine oilthrough said heat interchanger in heat interchange relationship with aliqueed refrigerat-` ing medium, whereby the refrigerating medium is atleast in part vaporized, a compressor for compressing the said vapor toa pressure at which it may be condensed at normal temperatures, acondenser for condensing the compressed vapor for 'reuse in the heatinterchanger, a conduit bypassing vapor from the high-pressure side tothe low-pressure side of said compressor, a valve rcontrolling thequantity of vapor passing through engine oil through said heatinterchanger in heat interchange relationship with a liquefiedrefrigerating medium, whereby the refrigerating medium is at least inpart vaporized, a compressor for compressing the said vapor to apressure at which it may be condensed at normal temperatures, means fordriving said compressorfrom said engine, and a condenser for condensingthe compressed vapor for reuse in the heat interchanger, said condenserincluding an air inlet opening to theA exterior of said aircraft and anair outlet connected to the carbureter air supply of said engine,whereby air is drawn through vsaid condenser in heat interchangerelationship with said compressed vapor.

4. An oil cooler for an internal combustion engine comprising, incombination, a heat inter- 1 changer, means for circulating hot engineoil through said heat interchanger in heat interchange relationship witha liquefied refrigerating medium, whereby the refrigerating medium is atleast in part vaporiz'ed, a compressor for compressingthe said vapor toa pressure at which it may be condensed at normal temperatures, acondenser for condensing the compressed vapor l for reuse in the heatinterchanger, a conduit bypassing vapor from the high-pressure side tothe low-pressure side of said compressor, a valve controlling thequantity of Vapor passing through said conduit, a valve stem on whichsaid valve is mounted, means responsive to the temperature of oil insaid heat interchanger for actuating' said valve,l said means includinga lever with which said valve stemds operatively connected, a pivotvabout which said `lever moves, and means for moving said pivot to Varythe operative range of said temperature responsive means.

5. An oil cooler for an internal combustion engine comprising, incombination, a heat interchanger including a plurality of U-shaped tubesadapted to contain a'liqueed refrigerating medium, means for circulatinghot engine .oil

Athrough said heat interchanger and over said tubes, a refrigerantsupply chamber positioned above said heat interchanger and into whichsaid tubes open, a float-actuated valve determining the liquid level insaid chamber, a comfor reuse in the heat interchanger, said condenserincluding an air inlet and an air outlet, the latter connected to thecarbureter air supply of said engine, whereby air is drawn through saidcondenser in heat interchange relationship with said compressed vapor, aconduit by-passing vapor from the high pressure side to the low pressureside of said compressor, and a valve controlling the quantity of vaporpassing through said conduit.

7. An oil cooler for an internal combustion engine comprising, incombination, a heat interchanger, means for circulating hot engine oilthrough said heat interchanger in at interchange relationship with aliquefied ref igerating medium, whereby the refrigerating medium is .atleast in part vaporized, a compresscrfor compressing Athe said Vapor toa pressure at which it may be condensed atnormal temperatures, acondenser for condensing the compressed-.vapor for reuse in the heatinterchanger, said condenser including an air inlet and an air outletthe latter connected to the carbureter air supply of said engine,whereby air is drawn through said condenser in heat interchangerelationship with said .compressed vapor, a conduit by-passing vaporfrom the high pressure side to the .low pressure side of saidcompressor, a valve controlling the -quantity of. vapor passing through'said conduit, and means responsive to the temperature of said oil insaid heat interchanger for actuating said valve.

8. An oil cooler for an internal combustion engine comprising, incombination, a heat interchanger including a plurality of tubes adaptedto contain a liquefied refrigerating medium, means for circulating hotengine oil through said heat interchanger and over said tubes, arefrigerant supply chamber positioned above said heat interchanger andinto which said tubes open, a oatactuated Valve determining the liquidlevel in said chamber, a compressor, a conduit leading from said supplychamber above the liquid level therein to theinlet of said compressor, aconpressor, a conduit leading from said supply chamber, above the liquidlevel therein to the inlet of said compressor, a condenser, a conduitleading from the outlet of said compressor to said condenser, a conduitby-passing said condenserand leading vapor from the outlet to the inletofsaid compressor, `a valve controlling the quantity of vapor passingthrough said by-pass conduit,a second valve controlling the quantity 'ofvapor passing to said condenser, means responsive to the temperature ofoil in said heat .interchanger for actuating both said Valves, and

means for returning condensed refrigerating medium to said refrigerantsupply chamber.

l6. An oil .cooler for an internal combustion u engine comprising,incombination, a heat interchanger, means for circulating hot engine oilIthrough said'heat interchanger in heat interchange relationship with aliqueed refrigerating medium, whereby the refrigrating medium is atleast in part vaporize'd, a compressor for compressing the said vapor toa pressure at which it may be condensed at normal temperatures, a

condenser for condensing the compressed vapor denser, a conduit leadingfrom the outlet of said compressor to said condenser,- and means forreturning condensed refrigerating medium to said.

refrigerant supply'chamber. y

9. An oil cooler for an internal combustion engine comprising, incombination, a heat interchanger including aplurality of tubes adaptedto contain a liquefied refrigerating medium, means for circulating hotengine oil through said heat interchanger and over said tubes, arefrigerant supply chamber positioned above said heat interchanger andinto which said tubes open, avoatactuated valve determining the liquidlevel in said chamber, a compressor, a conduit leading from said supplychamber above the liquid level therein to the inlet of said compressor,-a con.- denser, a conduit leading from theoutlet of said compressor tosaid condenser, a conduit by-passing saidcondenser and leading vaporfrom the outlet to the inlet of said compressor, a valve controlling thequantity of Vapor passing through said by-pass`conduit, means responsiveto the temperature of oil in said heat interchanger for y actuating saidvalve, and means for returning condensed refrigerating medium to-saidrefrigerant supply chamber.

HENRY G; SGHWARZ.

